Since the beginning, humanity has been fascinated by the vastness of the universe. This fascination has spawned countless stories and theories aiming to explain our place in the larger universe. The truth is wilder than any fiction.
Here's a short crash course on the amazing things in our own solar system [A] ...
The Sun
We all know how important the sun is for the survival of life on Earth. It’s also pretty extraordinary in itself. The Sun is massive, containing approximately 99.85% of the mass of the entire solar system. That is 333,000 times the mass of the Earth or 1,047 times the second most massive object in the system -- Jupiter, the largest of the planets.
It’s also far away. Although close in comparison to other stars, it’s distance of 94.475 million miles means it would take 8 minutes and 20 seconds to get there at the speed of light, or 19 years to fly there at the speed of a commercial airliner (550 mph).
In fact, the Earth is precisely positioned relative to the sun. If the Earth were just one inch closer, it would raise the average global temperature by 0.18 degrees Fahrenheit. That seems small but would have a dramatic effect on climate patterns. The distance to the sun is the greatest single factor affecting our climate. Most of the climate change recorded to date has been due to a ‘wobble’ in the Earth’s axis rather than any other factor.
Mercury
Mercury is the closest planet to the Sun and is also the smallest planet in the solar system, barely larger than Earth's Moon. That’s fine because no one would want to live there – daytime temps can reach 800°F (430°C), and nights can dip to -290°F (-180°C).
Named after the Roman messenger of the gods, Mercury does a lot of moving: it revolves around the Sun once every 88 Earth days, completing its orbit faster than any other planet.
Venus
Venus has been called Earth's twin planet because they are very similar in size and composition. However, it wouldn't be a very good vacation spot: Due to its incredibly dense atmosphere, Venus' mean surface temperature is even hotter than Mercury, at close to 876°F.
Venus is a quirky planet. It rotates clockwise, which is the opposite of Earth. From the surface, the Sun would appear to rise from the west and set in the east. In addition, Venus moves around the Sun faster than its rotation. That makes a year on Venus shorter than one of its days.
Earth
Our Earth is still the only planet known to support life. Slightly larger than Venus, Earth is the largest of the inner planets—the four rocky planets on this side of the asteroid belt. Beyond the belt, in the outer solar system, roam the gas and ice giants.
Earth is the only planet whose English name does not come from the name of a Roman or Greek deity. Instead, it has Old English roots, and it simply means "the ground."
Ask anyone who lives here – it’s definitely the best planet in the universe.
The Moon
Our Moon is the fifth largest moon in the solar system. While it's nearby in astronomical terms, it's still quite far—it sits a surprising 238,855 miles away from Earth. Thirty Earth-sized planets would fit in the distance between us and our closest celestial companion.
Interestingly, the moon has a chemical composition different from the Earth. The lunar surface contains a high proportion of non-crystalline glass formed from the apparent melting of rocks containing its four major minerals: plagioclase feldspar, pyroxene, olivine, and ilmenite. Scientifically speaking, it is perfectly formed and positioned to reflect light. You might even say it was created for that purpose.
Mars
The fourth planet from the Sun is easily recognizable in the night sky—it shines brightly and with a distinctly red coloration. This has earned Mars its nickname, "the Red Planet," a moniker fitting for a planet named after the Roman god of war.
Mars is one of the five planets—Mercury, Venus, Mars, Jupiter, and Saturn—that are visible to the naked eye. Ancient astronomers could tell them apart because of their constant movement against the sea of stars. That's the reason why the Ancient Greeks called these celestial objects planetes , meaning "wanderers."
The weather on Mars is not very inviting either. Because the atmosphere is so thin, heat from the Sun easily escapes Mars. The median surface temperature on the Red Planet is -85°F (-65°C) and gets as cold as -225°F (-153°C).
Ceres
You might not recognize Ceres as one of the planets in our solar system, that’s because it’s technically not a full planet -- it's the largest object in the asteroid belt. It is one of the four largest objects that make up 60% of the mass of the asteroid belt : Ceres, Vesta, Pallas, and Hygiea.
When it was first discovered in 1801, it was announced as a new planet. However, when more and more similar objects were discovered in the region, Ceres' classification was revised to that of an asteroid, and it ultimately became a dwarf planet in 2006.
Jupiter
Just beyond the asteroid belt we enter a realm of giants, and Jupiter is the biggest among them. The second most massive object in the solar system—after the Sun itself—Jupiter is so large that it contains more than twice the mass of all the other planets combined. The entire Earth would fit snugly in Jupiter's iconic Great Red Spot.
Jupiter is a gas giant with a stormy atmosphere, made primarily of hydrogen and helium. It has been probed by automated spacecraft, starting with NASA's Pioneer 10 in 1973. Despite its size, Jupiter doesn’t have a true surface. It’s mostly swirling gases and liquids – more like a bottomless ocean.
Europa
While Jupiter has no terra firma, it has more than 90 known moons. The largest of these is Europa, along with Ganymede, and Callisto, which are part of a select group called the Galilean moons. They were named in honor of Galileo, who first spotted them in 1610 with his homemade telescope. Nowadays, if you know where to look, they can be easily spotted with nothing but a pair of binoculars.
Europa has an icy surface that could hide a vast saltwater ocean beneath. According to NASA, this might make it a promising candidate as a place capable of supporting life beyond Earth (if they don’t mind living on an ice planet).
Saturn
Saturn is the farthest and dimmest planet that can be seen in the night sky with the unaided eye. As such, it's the furthest one that humanity has known of since ancient times. It is named after the Roman god of time and agriculture.
Saturn is best known for its spectacular rings. The rings were first observed—you might have guessed it—by Galileo Galilei in 1610, but he was unable to identify what they were: He described them as Saturn's "ears." It wasn't until 1655 that Christiaan Huygens first described them as a disc surrounding the planet.
Titan
Saturn's largest moon is slightly smaller than Ganymede—Jupiter's largest moon—but it's still larger than the planet Mercury. On top of that, it's the only moon known to sustain a sizable atmosphere, and its icy crust is riddled with flowing rivers. However, instead of water, the rivers and seas on Titan's surface are primarily made up of methane and ethane.
Like Europa, Titan hides its water underneath a frozen shell—a vast subsurface ocean waiting to be explored. Who knows what mysteries lie beneath?
Uranus
Uranus is a planetary oddball. Besides sharing Venus' retrograde (clockwise) rotation, its axis is so tilted that it appears to be spinning on its side. It's a very cold and windy planet, with winds that can reach up to 560 miles per hour.
Uranus and Neptune are classified as ice giants. Their size and composition differ vastly from that of Jupiter and Saturn, the gas giants. They are sizeably smaller, and they have much higher concentrations of water, ammonia, and methane.
Neptune
We're approaching the end of our voyage, and we've finally reached the 8th and most distant planet in the solar system. The story of its discovery is unique among planets: Neptune's presence was mathematically predicted after observing unexplained disturbances in Uranus' orbit. Based on those predictions, Neptune was first observed in 1846 by astronomer Johann Galle.
The second of the ice giants, Neptune is a little smaller in volume than Uranus. However, it is also denser, and therefore slightly more massive. Its iconic blue color comes from traces of methane present in its atmosphere.
Pluto
A small rocky world on the outskirts of our cosmic neighborhood. Long considered to be the solar system's ninth planet, Pluto is named after the Roman god of the underworld. It sits in a region called the Kuiper Belt, a disc similar to the asteroid belt that encircles the outer solar system.
Pluto was demoted to a dwarf planet in 2006. Pluto's classification history is similar to Ceres: as more and more objects of similar characteristics were found in the Kuiper Belt, scientists were forced to either accept them all as planets or to change their definition.
Charon
Clever astronomers felt it was only fitting that Charon, Pluto’s largest moon, shares the name of the ferryman who carried the souls of the dead to the afterlife in Greek and Roman mythology.
Charon is uncharacteristically large for a moon: it has half the diameter and ⅛ of the mass of Pluto. On top of that, Charon and Pluto are mutually tidally locked, meaning that they always show each other the same face (just like the Earth and its moon).
A Vast Universe
For all its amazing complexity, our entire solar system is merely a spec in the surrounding universe!
Isaiah knew it...
The prophet Isaiah wrote about the imponderable scale of Creation when he described God’s incredible majesty and power.
(v12) Who has measured the waters in the hollow of his hand
and marked off the heavens with a span,
enclosed the dust of the earth in a measure,
and weighed the mountains in scales
and the hills in a balance?
(v18) To whom then will you liken God,
or what likeness compare with him?
(v21) Have you not known? Have you not heard?
Has it not been told you from the beginning?
Have you not understood from the foundations of the earth?
(v22) It is he who sits above the circle of the earth,
and its inhabitants are like grasshoppers;
who stretches out the heavens like a curtain,
and spreads them like a tent to live in;
(v25) To whom then will you compare me,
or who is my equal? says the Holy One.
(v26) Lift up your eyes on high and see:
Who created these?
He who brings out their host and numbers them,
calling them all by name;
because he is great in strength,
mighty in power,
not one is missing.
(v28) Have you not known? Have you not heard?
The Lord is the everlasting God,
the Creator of the ends of the earth.
~Isaiah 40:12-28
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